Question

Solve.

{2d−e=7d+e=5

Use the linear combination method.



The solution is (3, −1) .

The solution is (4, 1).

There is no solution.

There are infinitely many solutions.

Answer 1

The solution is (4, 1).

Explanation:

Our system is

`\left \{ {{2d-e=7} \atop {d+e=5}} \right.`

Since the coefficients of e are the same, we will add the two equations together to cancel it:

`\left \{ {{2d-e=7} \atop {+(d+e=5)}} \right. \\\\3d=12`

Divide both sides by 3:

3d/3 = 12/3

d = 4

Substitute this into the second equation:

4+e=5

Subtract 4 from each side:

4+e-4=5-4

e = 1

This makes the point (4, 1).

Answer 2

.hello :
2d−e=7....(1)
d+e=5.....(2)
(1)+(2) : 3d=12
d=4
subsct in (2) :
4+e=5
e=1
conclusion :
The solution is (4, 1).